AbstractUK guidelines recommend routine HIV testing in high prevalence emergency departments (ED) and targeted testing for HBV and HCV. The ‘Going Viral’ campaign implemented opt-out blood-borne virus (BBV) testing in adults in a high prevalence ED, to assess seroprevalence, uptake, linkage to care (LTC) rates and staff time taken to achieve LTC. Diagnosis status (new/known/unknown), current engagement in care, and severity of disease was established. LTC was defined as patient informed plus ⩾1 clinic visit. A total of 6211/24 981 ED attendees were tested (uptake 25%); 257 (4.1%) were BBV positive (15 co-infected), 84 (33%) required LTC. 100/147 (68%) HCV positives were viraemic; 44 (30%) required LTC (13 new, 16 disengaged). 26/54 (48%) HBV required LTC (seven new, 11 disengaged). 16/71 (23%) HIV required LTC (10 new, five disengaged). 26/84 (31%) patients requiring LTC had advanced disease (CD4 <350, APRI (AST-to-Platelet Ratio Index) >1, Fibroscan F3/F4 or liver cancer), including five with AIDS-defining conditions and three hepatocellular carcinomas. There were five BBV-related deaths. BBV prevalence was high (4.1%); most were HCV (2.4%). HIV patients were more successfully and quickly LTC than HBV or HCV patients. ED testing was valuable as one-third of those requiring LTC (new, disengaged or unknown status patients) had advanced disease.